1. Field of the Invention
The invention is in the field of computer aided design ("CAD") systems, and specifically relates to a system and method for providing texture mapping to a two-dimensional design system.
The present invention has specific application to the apparel and footwear design industries.
2. Background Description
In the field of computer aided design, one of the objectives of any CAD system is to display a realistic image of whatever is being designed on the graphic visual input/output device, e.g. cathode ray terminal ("CRT"), of the system. One technique for enhancing the realism of the generated image is to add detail to the surfaces or areas making up the image using a texture mapping technique. That has been employed in three-dimensional CAD systems, notably those used in making animated films. The objects designed on and displayed by such systems are represented internally by a data structure that reflects the three-dimensional topology of the object. The texture mapping algorithms incorporated into those systems use that topology as a guide for applying the texture over the surface of the object in a realistic manner. Procedural Elements for Computer Graphics by David Rogers, pp. 354-363 (McGraw-Hill 1985); "Texture and Reflection Computer Generated Images" by James F. Blinn and Martin E. Newell, pp. 542-547, Communications of the ACM, (Oct. 1976); "Simulation of Wrinkled Surfaces" by James F. Blinn, Computer Graphics, Vol. 12, Proceedings of SIGGRAPH (1978) pp. 286-292. In order to obtain that realism, the texture applied to any surface of the object that is not perpendicular to the viewing direction (line of sight) must show distortion to give the appearance of being "tipped away" from the viewer; the applied texture should be shaded the same as the object based on a light source at a given location; the texture should appear larger near the front of the object and smaller near the back due to perspective; and, the texture should not appear if it is mapped to a surface that is on the back of the object. Those are a few of the visual cues that a texture-mapping algorithm used in a three-dimensional CAD system can give a user to enhance the three-dimensional appearance of the object being designed.
Those systems, however, are complicated and require comparatively large, expensive computer systems. Moreover, there is a need to be able to provide texturing which would provide for a three-dimensional appearance for two-dimensional CAD systems.
In the case of a two-dimensional CAD system, the image on the graphic visual input/output device, i.e. CRT, may have been drawn freehand by the user or may be a digital photograph that was input via a video camera. In any case, the data structure describing the three-dimensional topology of the object or image being designed does not usually exist in a two-dimensional CAD system; hence there is no well-defined procedure by which surface detail may be "correctly" applied to the different parts of the image. That is the problem the present invention addresses.